> ⚠️ This integration is still experimental! Only node environments are supported currently, stay tuned for Deno support in the future!
This **[Astro integration][astro-integration]** makes it easy to optimize images in your [Astro project](https://astro.build), with full support for SSG builds and server-side rendering!
Images play a big role in overall site performance and usability. Serving properly sized images makes all the difference but is often tricky to automate.
This integration provides `<Image />` and `<Picture>` components as well as a basic image transformer, with full support for static sites and server-side rendering. The built-in image transformer is also replaceable, opening the door for future integrations that work with your favorite hosted image service.
The `astro add` command-line tool automates the installation for you. Run one of the following commands in a new terminal window. (If you aren't sure which package manager you're using, run the first command.) Then, follow the prompts, and type "y" in the terminal (meaning "yes") for each one.
If you run into any issues, [feel free to report them to us on GitHub](https://github.com/withastro/astro/issues) and try the manual installation steps below.
The default image transformer is based on [Squoosh](https://github.com/GoogleChromeLabs/squoosh) and uses web assembly libraries to support most deployment environments.
If you are building a static site or using an SSR deployment host that supports NodeJS, we recommend installing [sharp](https://sharp.pixelplumbing.com/) for faster builds and more fine-grained control of image transformations.
First, install the `sharp` package using your package manger. If you're using npm or aren't sure, run this in the terminal:
```sh
npm install sharp
```
Then, update the integration in you `astro.config.*` file to use the built-in `sharp` image transformer.
The included image transformers support resizing images and encoding them to different image formats. Third-party image services will be able to add support for custom transformations as well (ex: `blur`, `filter`, `rotate`, etc).
Astro’s `<Image />` and `<Picture />` components require the `alt` attribute, which provides descriptive text for images. A warning will be logged if alt text is missing, and a future release of the integration will throw an error if no alt text is provided.
If the image is merely decorative (i.e. doesn’t contribute to the understanding of the page), set `alt=""` so that the image is properly understood and ignored by screen readers.
The built-in `<Image />` component is used to create an optimized `<img />` for both remote images hosted on other domains as well as local images imported from your project's `src` directory.
In addition to the component-specific properties, any valid HTML attribute for the `<img />` included in the `<Image />` component will be included in the built `<img />`.
The output format to be used in the optimized image. The original image format will be used if `format` is not provided.
#### quality
<p>
**Type:** `number`<br>
**Default:** `undefined`
</p>
The compression quality used during optimization. The image service will use a default quality if not provided.
#### width
<p>
**Type:** `number`<br>
**Default:** `undefined`
</p>
The desired width of the output image. Combine with `height` to crop the image to an exact size, or `aspectRatio` to automatically calculate and crop the height.
Dimensions are optional for local images, the original image size will be used if not provided.
For remote images, the integration needs to be able to calculate dimensions for the optimized image. This can be done by providing `width` and `height` or by providing one dimension and an `aspectRatio`.
#### height
<p>
**Type:** `number`<br>
**Default:** `undefined`
</p>
The desired height of the output image. Combine with `width` to crop the image to an exact size, or `aspectRatio` to automatically calculate and crop the width.
Dimensions are optional for local images, the original image size will be used if not provided.
For remote images, the integration needs to be able to calculate dimensions for the optimized image. This can be done by providing `width` and `height` or by providing one dimension and an `aspectRatio`.
#### aspectRatio
<p>
**Type:** `number` | `string`<br>
**Default:** `undefined`
</p>
The desired aspect ratio of the output image. Combine with either `width` or `height` to automatically calculate and crop the other dimension.
A `string` can be provided in the form of `{width}:{height}`, ex: `16:9` or `3:4`.
A `number` can also be provided, useful when the aspect ratio is calculated at build time. This can be an inline number such as `1.777` or inlined as a JSX expression like `aspectRatio={16/9}`.
> This is not supported by the default Squoosh service. See the [installation section](#installing-sharp-optional) for details on using the `sharp` service instead.
> This is not supported by the default Squoosh service. See the [installation section](#installing-sharp-optional) for details on using the `sharp` service instead.
> This is not supported by the default Squoosh service. See the [installation section](#installing-sharp-optional) for details on using the `sharp` service instead.
The list of sizes that should be built for responsive images. This is combined with `aspectRatio` to calculate the final dimensions of each built image.
```astro
// Builds three images: 400x400, 800x800, and 1200x1200
A `string` can be provided in the form of `{width}:{height}`, ex: `16:9` or `3:4`.
A `number` can also be provided, useful when the aspect ratio is calculated at build time. This can be an inline number such as `1.777` or inlined as a JSX expression like `aspectRatio={16/9}`.
> This is not supported by the default Squoosh service. See the [installation section](#installing-sharp-optional) for details on using the `sharp` service instead.
> This is not supported by the default Squoosh service. See the [installation section](#installing-sharp-optional) for details on using the `sharp` service instead.
> This is not supported by the default Squoosh service. See the [installation section](#installing-sharp-optional) for details on using the `sharp` service instead.
This is the helper function used by the `<Image />` component to build `<img />` attributes for the transformed image. This helper can be used directly for more complex use cases that aren't currently supported by the `<Image />` component.
This helper takes in an object with the same properties as the `<Image />` component and returns an object with attributes that should be included on the final `<img />` element.
This is the helper function used by the `<Picture />` component to build multiple sizes and formats for responsive images. This helper can be used directly for more complex use cases that aren't currently supported by the `<Picture />` component.
This helper takes in an object with the same properties as the `<Picture />` component and returns an object attributes that should be included on the final `<img />` element **and** a list of sources that should be used to render all `<source>`s for the `<picture>` element.
The integration can be configured to run with a different image service, either a hosted image service or a full image transformer that runs locally in your build or SSR deployment.
> During development, local images may not have been published yet and would not be available to hosted image services. Local images will always use the built-in image service when using `astro dev`.
The `serviceEntryPoint` should resolve to the image service installed from NPM. The default entry point is `@astrojs/image/squoosh`, which resolves to the entry point exported from this integration's `package.json`.
The `logLevel` controls can be used to control how much detail is logged by the integration during builds. This may be useful to track down a specific image or transformation that is taking a long time to build.
During static builds, the integration will cache transformed images to avoid rebuilding the same image for every build. This can be particularly helpful if you are using a hosting service that allows you to cache build assets for future deployments.
Local images will be cached for 1 year and invalidated when the original image file is changed. Remote images will be cached based on the `fetch()` response's cache headers, similar to how a CDN would manage the cache.
By default, transformed images will be cached to `./node_modules/.astro/image`. This can be configured in the integration's config options.
Image files in your project's `src` directory can be imported in frontmatter and passed directly to the `<Image />` component. All other properties are optional and will default to the original image file's properties if not provided.
Files in the `/public` directory are always served or copied as-is, with no processing. We recommend that local images are always kept in `src/` so that Astro can transform, optimize and bundle them. But if you absolutely must keep an image in `public/`, use its relative URL path as the image's `src=` attribute. It will be treated as a remote image, which requires an `aspectRatio` attribute.
Alternatively, you can import an image from your `public/` directory in your frontmatter and use a variable in your `src=` attribute. You cannot, however, import this directly inside the component as its `src` value.
Remote images can be transformed with the `<Image />` component. The `<Image />` component needs to know the final dimensions for the `<img />` element to avoid content layout shifts. For remote images, this means you must either provide `width` and `height`, or one of the dimensions plus the required `aspectRatio`.
The `<Picture />` component can be used to automatically build a `<picture>` with multiple sizes and formats. Check out [MDN](https://developer.mozilla.org/en-US/docs/Learn/HTML/Multimedia_and_embedding/Responsive_images#art_direction) for a deep dive into responsive images and art direction.
